The left side of my mouth tastes weird, could it be periodontal disease?

Yes.: However, this may also be a sign of a draining infection. The teeth need to be evaluated for any caries / infection which may leading to drainage.

Perhaps: A bad taste in the mouth can certainly be from periodontal disease. I would see a dentist or periodontist for evaluation. Especially is there is gum tenderness, swelling, redness or bleeding. That includes bleeding when brushing, flossing or eating. It can also be spontaneous. It can be an early stage of gum disease, or much more advanced. The only way to no is to be examined.

Posibly: "weird taste" could be many things. Acute infection draining puss, galvanism, cancer of the parotid gland are tooth decay are among the possibilities.

Yes, or.......: Yes, but there are many other possibilities such as cavities, stagnant food between your teeth, infection, dental plaque, broken filling collecting food, etc. See your dentist for a thorough exam and cleaning.